Flight level indicating instrument



` "POINTERl Aug;28, 1945. l B; w.-H. cocKs 2;,383458.

. A FLIGHT LEVEL INDICATING INSTRUMENT v @Filed sept. 18,l 1940 5 TA170NMY NORTH .S51-:KING

E y i Patented Aug. 28, 1945 2,383,468 FLIGHT LEVEL INDICATING INSTRUMENT t 'Basil William Henry Cocks, Middle Park, Victoria, Australia Application September 18, 1940, Serial No. 357,200 In Australia October 13, 1939 8 Claims.

This invention has reference to a means for indicating the liight level of air-craft to avoid collision when flying in a predetermined direction and. has been devised to provide a method and apparatus'positive in operation and convenlent and simple in use.

Hitherto it has been the accepted practice for air-craft, when flying in opposite directions between two points, to veer to the left or right depending on local regulations or to fly at respective odd and even thousand feet in order to avoid 4any possibility of collision whilst in mid-air. Furthermore, stipulated zones are provided for airmail planes within and along which zones private planes are not permitted to travel, with the result that such private planes have to make a detour to avoid the airmail route.

Other systems and means have been employed in an endeavour to avoid air-craft colliding in mid-air, such as charts or manually operated rotating tabulators, indicating different height zones in which the air-craft should be, when nying Within a range between two directional points, but such charts have many disadvantages,

' chart and the commencement of the first zone on the succeeding chart, such gap being, for example, 400 feet, within which zone no provision is made for air-craft to be flown. This gap would occur every 4000 feet if the zones were arranged to provide a distance of 1800 feet between aircraft flying in opposite directions.

Such accepted practices as above mentioned apply in some countries, while other countries allocate flight levers above which private planes are not permitted to ily, in order to avoid same coming within the zone where airmail or commercial planes are operating, with the result that such. private planes are often subjected to adverse weather coonditions which would be avoided if' they'were permitted to fly at a higher vention consists in a directional flight level indicating instrument, the dial of which is graduated and marked with suitable figures in defined positions to indicate to the pilot at what altitude his air-craft must be flown or flying when travelling in any direction in order to avoid collision with other similarly equipped air-craft in mid-air 'iat the same time and flying in any other direction, the said instrument having associated therewith either a north seeking needle, or a needle operated by variations in barometric pressures, or a ,2000 feet. Under such conditions, if the two needles are maintained in a superimposed position, two air-craft flying in opposite directions will be in horizontal planes separated by 1000 feet,

-While all other aircraft Will #be in varying hori zontal planes according to the direction in which they are flying, under which conditions, the possibility of air-craft colliding in mid-air is avoided. The invention may be applied to an instrument having a north seeking needle operating in conjunction with either a dial fixed in relation to the air-craft or an adjustable bezel adapted to be fixed in relation to the air-craft.

The invention may also be applied to a side reading instrument in which the dial floats and is controlled by a north seeking element, the said dial operating in conjunction with a lulober line fixed in relation to the air-craft.

Furthermore, if desired and convenient, the north seeking element may be located where 'desired in the air-craft and made to co-act with a remote controlled dial vertically or horizontally disposed on the instrument panel of the air-craft.

In any of the embodiments of the invention where a needle operable by variations in baro* metric pressures is used it will be appreciated that such barometrically controlled means must be adjusted to a fixed barometric pressure preferably the average pressure taken over a period throughout the world) in order that instruments incorporating such a needle in all machines will .operate in relationship to one another. Under such circumstances it would be necessary for safety purposes to incorporate an altimeter adapted to be adjusted yto the barometric pressure prevailing in different localities. However, such a condition does not raise any difculty in view of the fact that most air-craft machines at present carry two altimeters. y

Other features,A ofthe invention will be described hereinafter with reference to the accompanying drawing in which:

Figure 1 is a plan View of a dial of a horizontal form of direction level indicator having a north seeking needle and directional degree readings, and a co-acting needle operable by variations in barometric pressures.

Figure 2 is an elevation of the face of a side reading direction level indicator having dual dials operable for obtaining a similar result to the indicator illustrated in Figure l, the respective dials being controlled by a north seeking element and barometrically operable means.

Fig. 3 is a View of a modified form of indicator generally similar to the arrangement shown in Fig. 1 excepting that in the structure shown in Fig. 3 the dial having degree indications thereon moves with the north-seeking member while the compass indicator is xed to move with the aircraft.

It will be appreciated that the altimeter to be used in conjunction with the indicators herein described must be adjusted to a fixed barometric pressure (preferably -the average pressure taken over a period throughout the world), in order that such indicators in all machines'will operate in correct relationship to one another. Furl thermore, in the indicators hereinafter described where means are incorporated and operable b-y variations in barometric pressures, such barometrically controlled means must also be similarly adjusted to a fixed barometric pressure.

In one form of carrying the invention into practical `effect and referring to Figure 1 of the drawing, II represents the dial of a horizontal direction level indicator, such dial II having associated therewith a revolvable northl seeking needle I2, and an independent revolvable needle I3 operable by variations in barometric pressures.

The circumference of the dial IIr is graduated in degrees as at I4 for the full 360, and marked in an anti-clockwise manner from zero to 360,

in order that the north seeking needle I2 will in' dicate to the pilot the'degrees in which his aircraft is heading or flying.l

The barometrically operated needle I3 is arranged to rotate in an anti-clockwise direction when the air-craft is ascending, and to make one complete revolution over a height between two predetermined altitudes, depending on the clearance desired between two air-craft flying in opposite directions, for example, if 1000 feet clearance is desired between such opposing aircraft, the needle I3 would be arranged to make one complete revolution every 2000 feet altitude.

In operation when the air-craft is flying at the degrees as indicated by the needle I2, the pilot maintains the barometrically operated needle I3 in a superimposed position with the needle I2, thus ensuring that his air-craft is at all times located at the correct altitude to avoid collision with other air-craft in mid-air at the same time and flying in any other direction.

As before mentioned, the needle I3 is adjusted to a fixed barometric pressure, and to obtain the actual altitude at which the air-craft is flying, the al'timeter adjusted to the barometric pressure prevailing in the locality where the air-craft is at the time, must be consulted.

Should it be necessary to y in the same direction at a higher or lower altitude, the pilot must respectively ascend or descend in a spiral manner until the needle I3 makes one or more complete revolutions, both needles I2 and I3 being maintained in a superimposed position during the ascending or descending period to ensure that ,collision will not occur with other air-craft in midair at the same time and flying in other directions.

It will be appreciated that as long as the two needles I2 and I3 are maintained in a superimposed position it is impossible for an. air-craft incorporating the indicator to collide with any other air-craft in mid-air at the same time and flying in any other direction, providing similar indicators are incorporated in such other aircraft.

In order to facilitate the needies l2 and la' being maintained in .co-relation to one another,

the top needle I3 is vprovided with an enlarged end I5 having a cut-out I6 through which the' needle I2 may be viewed when in correct relationship. i

tions are in correct relationship to one another. It will be appreciated that where the needle I2 is remote controlled by' a north seeking element, the said needle I2' may be arranged to rotate in a clockwise manner instead of anticlockwise, under which condition, the graduated degree readings I4 would be marked also in a clockwise manner from zero to 360 and' likewise Ithe barometrically operated needle I3 would be arranged to rotate clockwise when the air-craftis ascending.

In a modified form of construction, Figure 2 represents a side reading indicator having dual: ribbon dials operable for obtaining a similar result tothe indicator described with reference to Figure 1, only instead of employing the fixed graduated dial II and movable jneedles I2 and` I3, the side reading indicator employs revolvable y graduated ribbon dials C and L which correspond to the respective revolvable needles I2 and I3 of the indicator illustrated in Figure 1, the

said dials C and L co-acting with a lubber line Il fixed on the face I8 of the indicator.

The ribbon dial C is revolvable around a vertical axis and is operated by a north seeking ele--l ment (not shown) in a similar manner to anv existlng side reading air-craft compass, said dial C being graduated as at I9 in degrees in a clockwise manner for the full 360 also in a similar manner to existing air-craft Compasses,-

so that when the air-craft turns to the right the z lubber line I'I moves in a clockwise direction.;

around the dial C. Y f

The barometrically operated dial L is arranged to make one complete revolution over a prede-1l termined height as does the needle I3 ofthe indicator described with reference to Figure 1, for example, every 2000 feet, thereby giving a y clearance of 1000 feet between two air-craft ilying in opposite directions.

4 The dial L is arranged to rotate in a clockwise direction when the air-craft is ascending and inan vanti-cloczkwise direction on descending.

The adjacently 'disposed and axially operated revolvable ribbon dial L is independently oper-` able by variations in vbarometric pressures in a similar manner to the needle I3 ofthe indicator illustratedV in Figure -1, the said ribbon dial L having amarking 2l) of a suitable nature, for example, an X on the vertical :face of its periphery and also degree readings arranged oppositely to those on dial C topermit the -said dialL to be maintained in correct relationship tothe dial C for flyingat the correct altitude when travelling in any direction.V Means are also provided where required on the dial L, such as the Words Ascend and Descend with respective associated arrows 12| and 22 to indicate to the pilot Whether to ascend or descend to an altitude in order to bring the marking 20 or correspondingdegree readings on the dials C and L into superimposed alignment with the lubber line I1.

In operation when the aircraft is ying in any direction as indicated on the dial C by the respective graduation I9 in alignment with the lubber line I1, the corresponding degree reading on the dial L must be maintained in alignment with the lubber line I1, under which condition the aircraft will be located at the correct altitude to avoid collision with other aircraft in midair flying in a different direction in the same locality at the same time. For example, if the aircraft is ying north on a magnetic bearing the zero or N line on the dial C will coincide with the lubber line I1, and the pilot should maintain an altitude at which the dial L will have its zero line or marking 20 in alignment with the lubber line. If the flying course is changed so that the compass reading of 15 on dial C is in alignment With the lubber line I1, then the pilot must cause the aircraft to descend until the reading of 15 on dial L is in alignment With the lubber line I1. This will bring the aircraft to the proper altitude for the direction in which it is flying.

Although the invention has been described as applying to horizontal and side reading indicators, it is to be understood that the invention is also applicable to other types of indicators, for example, the gyroscopic type, or the remote control type. Furthermore, in lieu of the north seeking needle and xed dial, the invention is also applicable to an indicator having a north seeking dial and a fixed needle, in which latter instance the notation of the respective graduations and degrees would require to be reversed Where necessary, from an anti-clockwise to a clockwise direction. Such an indicator is shown in Fig. 3.

I claim:

1. A directional flight level indicating instrument comprising a dial having indicated direction degree readings circumferentially disposed thereon and associated with a north seeking needle adapted to indicate on the degree readings the direction in which an air-craft is flying, an independent needle axially disposed in rel-ation to the north seeking needle and operable by variations in barometric pressures, the said barometrically operated needle being arranged to make one complete revolution around the dial over an adopted standard change of altitude whereby the altitude of the air-craft in relation toits flying direction is determined by maintaining the barometrically operated needle-.andthenorth 'seeking'` needle in a superimposedA position, for vthe purposes specified.

- 2; r A `directional flightl level. indicating instrument .afhavingi4 twoaxially mounted circular side reading, dials'horizontally disposed, one dial being.controlled by a north seeking element, the other dialbeing operable by variations in barometric pressures` to make one complete revolutionfoveifaepredetermined change` of altitude, the saida dials being-revolvable: independently of one. another,A indicated degree .readings vertically located on thev peripheral face of the north seeking dial, and; indicated degree readings located onthe peripheral face of the barometrically controlled dial, a lubber line fixed to the instrument face andfor useA in` conjunction with the degree readings' ,o f thenorthseeking dial and of the barometrically controlled dial -to denote the direction in which an' air-craft is flying, all for the purposes specified.

3. A directional night level indicating instrument for use with air-craft comprising a revolvable north seeking dial having directional degree readings circumferentially disposed in a clock- Wise manner thereon, an axially disposed needle associated with said readings and xed in relation to the air-craft, an independently revolvable needle responsive to variations in barometric pressures, the said latter needle being adapted to make one complete revolution around the north seeking dial over an adopted standard change ofy altitude, and to move in unison with the revolvable north seeking dial, the said needle, when maintained in a predetermined position relative to said dial, indicating that the aircraft is at the correct altitude in accordance with the direction in which it is flying, all for the purposes specified.

4. A directional iiight level indicating instrument for use with air-craft, comprising a revolvable north-seeking element, a stationary member cooperating with said revolvable element so that the positionof said revolvable element relative to said i stationary element indicates the direction of flight, an independently revolvable element adapted to be operated `by variations in barometric pressure and mounted for rotation on the same axis, with the rst said revolvable element, said independently revolvable element being adapted to make one complete revolution over an adopted change of standard altitude, and to remain fixed relative to the first said revolvable element when the air-craft is at a predetermined correct altitude in accordance with the direction in which it is ying, all for the purposesl specified.

5. A directional fiight level indicating instrument for aircraft including means adapted to be operated by a change of direction and means adapted4 to be oper-ated by a change of altitude, characterized by both said means being mounted for movement about a common axis to indicate K by a single relative position of both said means to eachother when an aircraft in which the instrument is fitted is flying at a correct flight level relative to the direction of travel to prevent collision of aircraft flying in different directions.

6. A directional iii'ght level indicating instrument for aircraft including an altitude indicating element, an element adapted to be operated by a change of direction of night, and a direction indicating means, characterized by both said elements being mounted for movement about a common axis to indicate by a single position when an aircraft in which thev instrument isy tted is flying at a correct flight level in any direction. v Y l 8. A directional ight level indicating instrument comprising a dial having -indicated'altltude graduations circumferentially disposed y thereon with adjacently disposed Aindicated degree readings located in defined relationship to the said altitude graduations, means adapted to be operated by changes in the barometric pressure `as'- sociated with said graduations and readings and adapted to make one complete'revolution around th dial when the aircraft moves from one predetermined `altitude to another, and anorth seeking element mounted for rotation about an axis common to` the axis of said barometric pressure operated means, said north seeking ele-` ment, said barometric :pressure operated means and said degree readings, and' altitude graduatlons assuming a single relative position when the aircraft is'ying at the altitude'which is proper for the direction of flight.4

BASIL WILLIAM HENRY COCKS. 

